The primary objective of this study is to determine if adolescents receiving combination antiretroviral therapy and maintaining undetectable viral load for a two year period of time achieve improvement in immune status. There is evidence from the REACH study that adolescents have a unique immunologic response to HIV infection. (1). In that study, investigators found that adolescents had a unique increase in nave CD8 + T lymphocytes. This suggests that adolescents have a functioning thymus gland, unlike many adults, and therefore may have greater recovery of immune functions following initiation of highly active antiretroviral agents. In addition, adolescents may begin therapy earlier than adults, before there is significant immunologic damage. In PACTG 381, subjects who are enrolled into the study are placed on a minimum of three FDA approved, antiretroviral agents. One of the agents must either be a protease inhibitor or the non-nucleoside reverse transcriptase inhibitor, efavirenz. It has been found that these agents offer the greatest hope for maximal suppression of viral replication for the longest duration of time. Adolescents who are enrolled into this study are then followed very closely studying two specific areas. The first entails viral dynamics. The purpose of these studies are to see if those adolescents who have a more rapid response to mediation are better able to achieve long-term viral suppression. The second involve a battery of immunologic studies, looking at both cell numbers as measured by three-color flow cytometry measures and function through both delayed type hypersensitivity studies and lymphocyte proliferation studies.